abstract class Animal {
    public abstract void eat();
    public abstract void sleep();
    public abstract void think();
    public abstract void speak();
}

class Cat extends Animal{
    public Cat() {
    }

    @Override
    public void eat() {
        System.out.println("cat is eating");
    }

    @Override
    public void sleep() {
        System.out.println("cat is sleeping");
    }

    @Override
    public void think() {
        System.out.println("cat is thinking");
    }

    @Override
    public void speak() {
        System.out.println("cat is speaking");
    }
}
class Bird extends Animal{
    public Bird() {
    }

    @Override
    public void eat() {
        System.out.println("bird is eating");
    }

    @Override
    public void sleep() {
        System.out.println("bird is sleeping");
    }

    @Override
    public void think() {
        System.out.println("bird is thinking");
    }

    @Override
    public void speak() {
        System.out.println("bird is speaking");
    }
}
class Human extends Animal{
    public Human() {
    }

    @Override
    public void eat() {
        System.out.println("human is eating");
    }

    @Override
    public void sleep() {
        System.out.println("human is sleeping");
    }

    @Override
    public void think() {
        System.out.println("human is thinking");
    }

    @Override
    public void speak() {
        System.out.println("human is speaking");
    }
}

class Num_6{
    public static void main(String[] args) {
        Human human=new Human();
        human.eat();
        human.sleep();
        human.speak();
        human.think();
        Cat cat=new Cat();
        cat.eat();
        cat.sleep();
        cat.speak();
        cat.think();
        Bird bird=new Bird();
        bird.eat();
        bird.think();
        bird.speak();
        bird.sleep();
    }
}
